@misc{_M_[1939],
 copyright={Public Domain},
 address={Gotha},
 journal={Vogels Karte von Mitteleuropa. Fliegerkarte},
 howpublished={online},
 year={[1939]},
 publisher={Justus Perthes},
 language={ger},
 title={M 33 - SW Passau},
 type={Image},
 URL={http://www.rcin.org.pl/Content/210177/PDF/WA51_191528_PTGC61-18-r1939_M-33-SW-Passau_0001.pdf},
}